Question 1: Define a reversible reaction in your own words.

Answer: A reversible reaction is a chemical reaction where the products can react to form the original reactants, and the process can proceed in both forward and backward directions.

Question 2: Explain the significance of the equilibrium position in a reversible reaction.

Answer: The equilibrium position indicates the ratio of products to reactants when the forward and backward reactions occur at the same rate, meaning the concentrations remain constant over time.

Question 3: Describe a real-world example of a reversible reaction.

Answer: The formation and dissociation of ammonia (NH₃) in the Haber process is a reversible reaction.

Question 1: In a reversible reaction, at equilibrium, the concentration of reactants is 0.3 mol/dm³ and that of products is 0.7 mol/dm³. Calculate the equilibrium constant (Kc).

Answer: Kc = [Products] / [Reactants] = 0.7 / 0.3 ≈ 2.33

Question 2: A reversible reaction has a forward rate constant (k₁) of 0.5 s⁻¹ and a backward rate constant (k₂) of 0.2 s⁻¹. Calculate the ratio of the forward to backward reaction rates.

Answer: Rate ratio = k₁ / k₂ = 0.5 / 0.2 = 2.5

Question 1: Design a simple experiment to investigate the effect of concentration on the rate of a reversible reaction, such as the reaction between iodine and thiosulphate. Include variables to control and safety precautions.

Answer: To investigate the effect of concentration on the rate of the iodine-thiosulphate reaction, prepare solutions of varying iodine concentration while keeping other conditions constant. Mix each with a fixed amount of thiosulphate and record the time taken for the reaction to complete, indicated by a colour change. Control variables include temperature, volume, and catalyst presence. Safety precautions involve wearing goggles and gloves due to iodine's staining and potential irritant properties.

Question 2: Identify two variables that could affect the outcome of a reversible reaction experiment and explain how they should be controlled.

Answer: Variables such as temperature and concentration can affect the reaction rate. They should be kept constant to ensure valid results, for example, by using a water bath to control temperature and measuring solutions accurately.

Question 1: In an experiment, the concentration of reactant A decreases from 1.0 mol/dm³ to 0.4 mol/dm³ over 10 minutes, while the concentration of product B increases from 0 mol/dm³ to 0.6 mol/dm³. Explain what this data suggests about the reaction's equilibrium.

Answer: The data indicates that the reaction is proceeding forward, forming product B from reactant A, and has reached or is approaching equilibrium where concentrations are stabilising.

Question 2: If the concentration of reactant A remains constant after 10 minutes, what does this imply about the reaction?

Answer: It implies that the reaction has reached dynamic equilibrium, with the forward and backward reaction rates being equal.

Question 1: Describe how reversible reactions are utilised in the manufacturing of fertilisers such as ammonia.

Answer: The Haber process uses a reversible reaction where nitrogen and hydrogen gases react to form ammonia; conditions are controlled to optimise the equilibrium position for maximum yield.

Question 2: Explain why reversible reactions are important in biological systems, providing an example.

Answer: Reversible reactions allow biological systems to respond dynamically to changes. An example is the carbon dioxide-bicarbonate buffer system in blood, which maintains pH balance.